Reaction products of diazotised 4'-aminoazobenzene-4-sulphonic acid, coupled with resorcinol and diazotised sodium 4-aminobenzenesulfonate, sodium salts

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

non mutagenic

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

According to Annex VII of the REACH Regulation (EC 1907/2006) and ECHA Guidance Chapter R.7a: Endpoint specific guidance, Version 5.0 – December 2016, a preliminary assessment of mutagenicity should normally include data from a gene mutation test in bacteria unless existing data for analogous substances indicates that this would be inappropriate. When the result of the bacterial test is positive, it is important to consider the possibility of the substance being genotoxic in mammalian cells, whereas a negative response would generally not require any further testing. However, if results from further studies of genotoxicity are available, it is recommended to take them into account in the assessement.

The AMES Mutagenicity potential of the substance was investigated using a specific QSAR model, developed to predict the skin AMES Mutagenicity potential for dyes. The existing QSAR models have strong limitations to predict ionic complex structures as the organic dyes are, and consequently they provide unreliable results. The QSAR modelling used was developed in accordance with the OECD principles (AMES MUTAGENICITY QSAR MODEL REPORT N. 07).

Based on the estimation, the substance is expected to be negative in the AMES Mutagenicity assay.

The estimation resulted to be in the applicability domain of the model.

In order to confirm the results obtained by the QSAR prediction, the investigation performed on the analogue substance Similar Substance 01 is used as support of the prediction. Justification for Read Across is given in Section 13 of IUCLID.

Genotoxic potential of Similar Substance 01 was examined in a standard battery of tests, which allowed to trace its genotoxic profile: in vitro gene mutation assays in bacteria (OECD 471), in vitro mouse lymphoma assay (OECD 476) and in vitro micronucleus assay (OECD 487).

 

A gene mutation assay at the thymidine kinase locus  (TK) in mouse lymphoma L5178Y cells was performed with and without metabolic activation at concentrations up to 6000 µg/ml. Cytotoxicity was not seen in the preliminary toxicity test, while it was detected at 6000 µg/ml in the second experiment after 24 hour of exposure with metabolic activation. Mutagenic effects were not noted, thus test substance was considered as not mutagenic in this assay.

 

A micronucleus test in Chinese hamster V79 cells was performed with and without metabolic activation. In a preliminary test (exp. I), precipitation was noted starting at 1470.5 and 2941 µg/ml without and with metabolic activation, respectively. Toxicity was noted starting at 1470.5 µg/plate both with and without metabolic activation. Based on results in exp. I, concentrations up to 3000 µg/ml were used in exp. II. No increase in micronucleated cells was noted, thus test substance was considered as not mutagenic in this assay.

 

As for bacterial gene mutation, in a study on Salmonella typhimurium strains TA 97, TA 98, TA 100 and TA 1535, no mutagenic effects were noted up to the highest concentration of 5000 µg/plate both with and without metabolic activation.

In a study on TA 98, TA 100, TA 102, TA 1535 and TA 1537 strains with and without metabolic activation, a marginal increase in mutant frequency was only noted in TA 98 strain without metabolic activation at the highest concentration tested of 18519 µg/plate, i.e. 5000 µg/plate based on a 27 % content of active ingredient over a 91 % total content of active substances.

However, considering that mutagenic effect on TA 98 strain:

- was seen in only one study, i.e. the one using a test sample with lower purity in terms of active ingredient,

- was described as marginal and was reported only at the highest tested dose

test substance was considered as not mutagenic in this assay.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), Annex I, Part 3, substances which cause concern for humans owing to the possibility that they may induce heritable mutations in the germ cells of humans are classified in Category 2. This classification is based on positive evidence obtained in:

— somatic cell mutagenicity tests in vivo, in mammals; or

— other in vivo somatic cell genotoxicity tests which are supported by positive results from in vitro mutagenicity assays.

Note: substances which are positive in in vitro mammalian mutagenicity assays, and which also show chemical structure activity relationship to known germ cell mutagens, shall be considered for classification as Category 2 mutagens.

In vitro mutagenicity tests are the following:

— in vitro mammalian chromosome aberration test;

— in vitro mammalian cell gene mutation test;

— bacterial reverse mutation tests.

Based on the responses in the available experimental studies and estimation, a genotoxic potential for target substance is excluded. Therefore, it is not classified according to the CPL Regulation (EC 1272/2008).